After a tick bite, when should a person have blood drawn for Lyme disease testing? - briefly
Blood should be drawn about 2–4 weeks after the bite, when specific antibodies are most likely to be detectable. Testing earlier may miss infection; a repeat sample is advised if symptoms appear later.
After a tick bite, when should a person have blood drawn for Lyme disease testing? - in detail
Blood should be drawn for Lyme serology after the immune response has had time to produce detectable antibodies. Initial IgM antibodies typically appear 2–3 weeks after the bite, while IgG antibodies become reliably measurable 4–6 weeks post‑exposure.
Timing recommendations
- If a rash or systemic symptoms develop: obtain a sample at least 3 weeks after the bite, preferably 4 weeks, to allow IgM detection.
- If no clinical signs are present but exposure risk is high: schedule the draw at 4–6 weeks to capture IgG seroconversion.
- If testing is performed earlier than 2 weeks: results are likely negative; consider repeat testing after the recommended interval if symptoms emerge.
Testing follows a two‑tier algorithm: an initial enzyme‑linked immunosorbent assay (ELISA) screened for antibodies, followed by a confirmatory Western blot if the ELISA is positive or equivocal. Early‑stage disease may yield a negative ELISA; a second sample taken after the 4‑week mark can reveal seroconversion.
In summary, collect blood no sooner than 2 weeks after the bite, with optimal accuracy achieved at 4–6 weeks, adjusting the schedule according to the appearance of clinical manifestations.